Obviously, the most important thing to do to win a bid is to offer the most money or the quickest, least painful closing timeline. But in a competitive market where bids are tight, a good letter can help.

A house is a very personal, intimate part of a family. Selling is not easy and not fun. It's not just a financial decision. A home has memories and emotions tied into it. When selling, you want to know that you're passing it along to the right people who will care for it as much as you did. And, if you care about your neighbors, you want some peace of mind that you're giving them good new people for the block.

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Stephanie O'Brien inspects the kitchen in a home for sale during an open house in San Francisco, California.

I am in the process of selling my second home and buying my third house in a five-year period. Hopefully, this one will be the "forever" home, and we won't be moving again.

When we sold our first house, the buyers sent us a wonderful note about why they wanted the house. They told a story about searching for the perfect home and how our house felt right. They talked about their family and how this house would be perfect for their home.

They also offered the best price, so there wasn't much debate. But selling the house to the highest bidders, who told us why they wanted the house, made us happy. It also sanded off any rough edges that may have come later in the selling process.

In the process of buying our third home, we wrote a letter to the sellers about why we wanted the house. We were offering significantly below the opening asking price, so we wanted to help the process in any way possible. This was not some sort of flip, or us trying to take advantage. We loved the home, loved the renovations, loved the neighborhood and wanted to raise our family in the home.

We won the bid. Did the letter help? Perhaps. Our broker told us the sellers wanted us to buy the house, and our broker implied that was because we fully appreciated all the work that had been done on the house.

While selling our second house, we got a letter from bidders who offered below our asking price. They lost the bid, but we were rooting for them to win because of their gracious letter. The winning bidders offered significantly more money, but no letter. If the bids had been tied, the letter writers would have won. If the bids had even been close — just a few thousand dollars apart — we might have gone with the letter writers.

Buying a house is an expensive, time-consuming process. A letter shouldn't take long to write, and it doesn't cost a thing. If you're buying a house, you'd be foolish not to do it.